| Common error messages
        Errors about RTC, the Linux real time clock
            device
        Video card memory errors
         Capture card problems
        Channels black-and-white and numbers
            off-by-one
        Too few buffers with bttv before
            kernel 2.4.21
        bttv takes a long time to load
        Audio problems with Prolink PixelView
            cards
        Poor performance with the rivatv driver
        Unable to tune to channels using the
            bttv, saa7134 or cx88 drivers
         Video card problems
        No YUY2 with the Radeon FireGL drivers
        Corrupted YUY2 video with EPIA onboard
            video
        Terrible XVIDEO performance with
            Radeon cards and XFree86 4.3
        Poor performance with SiS driver in XFree86 4.2.1
            and earlier
        XVIDEO always-on-top with some Radeon cards
        Corrupted image borders on NVIDIA cards
            in overscan modes
        No XVIDEO support on pre-GeForce NVIDIA
            cards with the "nv" driver
        Problems with NVIDIA TNT and TNT2 cards
        XVIDEO initialization problem with the savage
            driver
         Driver conflicts
        Using overlay mode in xawtv or zapping causes
            system instabilities
        apm driver known to cause frame drops
        ntfs driver known to cause frame drops
         Common error messagesEnhanced Real Time Clock support in your kernel can help applications
        like tvtime improve the smoothness of their output.  The kernel module
        that provides this feature is called rtc, and it is compiled and
        installed by default on most Linux distributions. This feature will improve the quality of tvtime's output, but is
        NOT required for tvtime to operate. Reasons why tvtime might not be able to use /dev/rtc include: 
        Your user does not have read/write access to the device
        file /dev/rtc.
        You compiled your own kernel and forgot to enable the RTC device.
        Your user does not have the rights to get high resolution timers.
         If your user does not have sufficient priviledge, the RTC device
        cannot be used for high-resolution timers.  To solve this, you can
        do one of the following: 
        Run tvtime as root.
        Set the tvtime executable SUID root using this command:chmod u+s /usr/bin/tvtime.
Allow user processes the ability to use high resolution timers
            by running this command as root every time your machine boots:sysctl -w dev.rtc.max-user-freq=1024
 tvtime uses the XVIDEO extension, which allocates video card
        memory.  We have experienced some problems where the X server fails
        to provide enough video card memory for tvtime to use it.  This can
        happen if your video card is old and simply doesn't have enough memory
        to hold the framebuffer and tvtime at once.  However, there are also
        bugs in X servers and X drivers that can cause this. If your distribution is using the
        Xorg X server and you
        are seeing these errors, please comment on
        Xorg bug
        474. Capture card problemsThe tuner driver defaults to detecting a PAL tuner on many NTSC
        capture cards, a notable example being the ATI TV Wonder cards.  This
        causes all of the cable frequencies to be out of alignment, channel
        numbers are off-by-one and slightly detuned.  To fix this, the tuner
        type must be told explicitly when loading your capture driver.  For
        example, with the bttv driver use the following: 
    modprobe bttv tuner=2
You may have to first remove the bttv module if it is already
        loaded.  To make this change automatic, in your
        /etc/modules.conf file, add the following line: 
    options bttv tuner=2
This will ensure that whenever the tuner module is loaded, it will
        use the correct tuner for this card.  If this does not fix the problem
        please post a bug report on
        the
        tvtime bugs page. In older versions of bttv, this module option could also be passed
        to the tuner module.  This method is deprecated in newer 2.6 kernels,
        and so you must pass the parameter to the capture driver itself. To attack this problem, we believe that the tuner module must be
        fixed to correctly detect the difference in tuner, as so many users
        are affected by this problem.  To help with this, please follow up on
        tvtime bug 711428. The popular bttv capture
        driver only provided applications with two buffers by default in
        versions shipped with kernels before 2.4.21.  Our advanced
        deinterlacing algorithms require a longer history of past input
        frames in order to predict motion in the video stream. To give applications more buffers, use this option when
        loading the bttv driver: 
    modprobe bttv gbuffers=4
To make this change automatic, add the following in your
        /etc/modules.conf file: 
    options bttv gbuffers=4
On some cards without a tuner, bttv can take a long time to load
        (a few minutes).  If you see this problem, try using this option
        in your modules.conf file for loading the i2c-algo-bit
        module: 
    options i2c-algo-bit bit_test=1
If that does not help, please post a bug report. The bttv driver seems to misdetect Prolink Pixelview cards pretty
        badly.  There are five Prolink cards listed in CARDLIST for the bttv
        driver: 
  card=16 - Prolink Pixelview PlayTV (bt878)
  card=37 - Prolink PixelView PlayTV pro
  card=50 - Prolink PV-BT878P+4E /
            PixelView PlayTV PAK /
            Lenco MXTV-9578 CP
  card=70 - Prolink Pixelview PV-BT878P+ (Rev.4C)
  card=72 - Prolink Pixelview PV-BT878P+9B
            (PlayTV Pro rev.9B FM+NICAM)
The bttv driver cannot seem to autodetect these cards correctly.
        We have found that cards which should use card=70 but are
        instead loaded using card=72 are causing audio mute/unmute
        to fail randomly, or even be inverted, resulting in no audio or just
        snippets of audio.  To avoid this, please make sure you are using the
        correct variant of this card.  Specifically, the rev 9D of
        the newer Pixelview cards should use card=70 and not
        card=72. By default, the rivatv the driver copies frames from video memory
        into system memory, which can harm performance.  Performance can be
        improved by using DMA to transfer the frames, however, this
        option only works when using the open-source "nv" driver in X,
        not with the NVIDIA binary drivers. You can turn on dma support as follows in your modules.conf
        file: 
    options rivatv dma=1
The bttv, saa7134, and cx88 drivers each support a wide variety
        of cards which all use the same chip.  In particular, these cards
        differ in what tuner they use, how many inputs they have, and how
        it is configured. Often, these drivers cannot autodetect the card type, or detect
        the incorrect card.  To debug this, you must watch your kernels logs
        by running the "dmesg" command, potentially loading and
        unloading the driver with different options until the driver is
        successfully loaded. Some hints: 
        If your card appears as UNKNOWN/GENERIC, then the
            tuner driver will not be loaded and the card will likely not
            work.  You will need to load the driver with the correct card
            number.
        If your tuner reports that it is using type -1, it is not loaded
            and you will not be able to tune any stations.
        If you are an NTSC user, make sure the tuner you are using announces
            itself as an NTSC tuner.
         For example, if you are using the bttv driver, the common
        procedure for setting up a card is as follows: 
        Run "modprobe bttv" with no options.
        Run "dmesg".  Check to see if your card is autodetected,
            and if the tuner is correct.  If everything looks fine, you're done.
        If the card appears as UNKNOWN/GENERIC, find the CARDLIST
            file in your kernel documentation and find your card in the list.
        Unload bttv and tuner using "rmmod bttv" and
            "rmmod tuner".
        Run "modprobe bttv card=X" where X is the number of
            your card.
        Run "dmesg" again.  See if the card loaded properly
            and if the tuner is correct.
        If not, unload bttv and tuner again, and try specifying the tuner
            type as well using "modprobe bttv card=X tuner=Y".
        Curse Linux for being so complicated.
         Video card problemsWith the Radeon FireGL drivers, the user has the option of having
        OpenGL use an overlay surface, giving 3D graphics without tearing,
        or video overlay surfaces for multimedia players.  This can be set
        in the Driver section of /etc/X11/XF86Config-4
        using: 
    Option  "VideoOverlay"       
or 
    Option  "OpenGLOverlay"      
For using tvtime, you MUST have selected
        VideoOverlay instead of OpenGLOverlay.  The
        tvtime bug report on this is
        bug 787142. We have received multiple reports that the binary XFree86 drivers
        from VIA for the EPIA onboard video have corrupted YUY2 overlay
        surfaces, and have problems with high framerate video.  We have
        also heard that these problems do not exist in the open source driver
        in XFree86 CVS.  More information on either driver and their status
        with tvtime would be appreciated. We have had numerous reports of horrible performance from
        Radeon cards and XFree86 4.3.  So far, nobody has been able
        to figure out conclusively what is going on here.  See the
        madness in
        XFree86 bug 414.
        The tvtime bug about this is
        bug 759804. The XVideo drivers in XFree86 versions up to 4.2.1 exhibit
        extremely poor performance.  This is fixed in later versions of
        the driver.  If you own a SiS card, please upgrade to the latest
        driver by Thomas Winischhofer, or upgrade to X 4.3 which includes
        a recent version of his driver.  The web page for the SiS driver
        is at http://www.winischhofer.net/linuxsis630.shtml. The tvtime bug report to on this is
        bug
        636338. Around the end of 2002, it was noted that with the ATI Radeon
        7000 card and the XFree86 4.2.1 packages in debian, XVideo windows
        are "always on top" and cannot be minimized.  This was also seen in
        RH8.0's XFree86 4.2 with a Radeon 32MB DDR, R100 QD (a 7200
        card?).  We have not researched this issue enough to know the extent of
        what cards are affected, or what versions will fix this.  More
        information on this would be appreciated. There is a bug in versions of the NVIDIA driver before
        1.0-4349 and the nv driver in 4.3.0 and earlier for cards
        which support wide filter kernels for high quality XVideo surfaces.  If
        the overscan value is larger than 0, then the card uses memory outside
        of the image for interpolating around the edges, causing corruption all
        around the outside of the tvtime window. NVIDIA was made aware of the problem and fixed it for driver release
        1.0-4349 and in the nv driver in CVS XFree86.  For
        reference, the tvtime bug on this was
        bug
        694144. The open source NVIDIA driver for X ("nv" not "nvidia") does not
        support XVideo surfaces for pre-GeForce cards like the TNT2.
        To use tvtime with these cards, you must use the binary drivers. The binary drivers give better performance for XVIDEO than the
        open-source driver, since it can use the kernel module component to
        negotiate DMA transfers for video frames.  Where possible, stick to
        the binary drivers when using tvtime on NVIDIA hardware. Corrupted framesThe TNT and TNT2 cards are very limited in their bandwidth, and this
        problem will appear as horizontal lines in the video output unless
        the monitor is at a low resolution.  Smaller output window sizes
        will make the problem worse, as the DAC will have to read out more data
        in the same amount of time.  This problem should not occur with any of
        the GeForce series cards. Card cannot downscaleA user of a NV5: RIVA TNT2 Ultra (rev 11) noted that the card
        cannot downscale video, it only crops it.  This is apparently a
        hardware deficiency of many TNT cards, and the XVIDEO API provides
        no way to detect this case. Poor performance at high resolution and refresh rateA user of a TNT2 Vanta card reported that blit performance
        was absolutely terrible until they went down to a resolution of
        800x600, at which point speed quadrupled.  We believe this is due
        to bandwidth problems on these cards. We've investigated a bug where the savage X driver does not
        initialize its XVideo subsystem unless it starts on a modeline where
        the resolution equals the virtual resolution.  That is, if you have
        a virtual resolution of 1600x1200, make sure you start on a
        1600x1200 mode, otherwise XVideo won't initialize. This bug was noted on the XFree86 devel list. Driver conflictsOverlay mode, as can be used in xawtv or zapping, causes system
        instabilities.  This is because their 'overlay' mode allows the capture
        card to write directly to video memory without locking it first, which
        is unsafe for many video cards, specifically those which do not use a
        linear framebuffer (such as NVIDIA cards with the binary drivers). Use of the xawtv/overlay mode has caused system crashes, and
        specifically, can cause tvtime to crash if it tries to use XVideo
        features after the framebuffer area has been destroyed by the capture
        card (see
        tvtime bug 702539). A workaround for having a no-CPU-access mode is to use the XFree86
        "v4l" extension, which allows safe use of the framebuffer by capture
        cards.  tvtime does not support using this mode, nor do we plan to,
        as we would not be able to composite our OSD on top of the video
        signal or perform any processing of the video. We had a problem report that in RH9 (later 2.4 kernel), the
        GNOME battery applet was polling apm every few seconds.  This caused
        the system to block for 50-100ms causing stutters in video
        playback. We had a problem report that having gkrellm running would cause
        frame drops in tvtime.  We believe this was due to the ntfs driver,
        as the frame drops occurred whenever gkrellm was monitoring the
        users' other disk that had ntfs partitions.  See
        tvtime bug 634674. |